<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>css初学</title>
    <style type="text/css">
        .panel{
            color: rgb(255,0,0);
        }
        .pane2{
            font-size: 30px;
        }
        .pane3{
            text-decoration: underline;
        }
    </style>
</head>
<body>
<p class="panel pane2">第一段</p>
<p class="pane2 pane3">第二段</p>
<p class="panel pane3">第三段</p>
</body>
</html>